1. Field of the Invention
The present invention relates o improvements in a floating magneic head used in a hard disk drive and, more particularly, to improvements in a floating magnetic head of the composite type.
2. Description of the Prior Art
A floating magnetic head of the composite type which has been heretofore frequently used is generally indicatd by reference numeral 1 in FIG. 17. This head 1 comprises a slider 2 made of barium titanate or calcium titanate together with rails 3 and 4 disposed on opposite sides of the slider 2. The top surfaces of the rails 3 and 4 form floating surfaces.
One rail 3 has a slit 5 of a given depth, the slit 5 extending in a direction perpendicular to the direction in which a magnetic recording medium (not shown) moves. A head core 6 made of a ferromagnetic substance such as a ferrite is inserted in the slit 5. The core 6 is rigidly mounted by sealing of glass or other means. Indicated by d is the track width. The slider 2 is provided with two cutouts 7 and 8 forming windows on opposite sides of the slit 5 receiving the head core 6. A coil 9 is wound on that portion of the core 6 which faces the windows 7 and 8.
In this conventional floating magnetic head 1 of this structure, the head core 6 is treated as an independent part until it is inserted into the slit 5 and so it has been difficult to reduce the thickness of the core below 100 microns. To cope with High frequency signals, the head core 6 must be made thinner. However, this thinning has been very difficult to accomplish.
Also, it has been necessary to measure the apex of the head core 6 sealed with glass. To adjust the height of the throat, it has been necessary to make a measurement obliquely via the glass inside the slit 5. The measurement may be affected by the refractive index of the glass or local distortion in the glass.
In recent years, the track width d has been reduced below 10 microns. Therefore, the ratio of the amount of the glass filled in the track width-adjusting groove in the head core 6 to the track width increases. Consequently distortion due to differences in coefficient of thermal expansion among the glass, the slider, and the head core (often consisting of a ferrite) increases, thus deteriorating the efficiency of the core 6.
Thus, to make the head core 6 cope with High frequency signals while maintaining the conventional shape, if the thickness is reduced, it is necessary to reduce the width of the slit 5. Therefore, it has been difficult to increase the depth of the slit beyond 1 mm, the slit having a thickness less than 100 microns. If only the thickness of the core is decreased while maintaining the large width of the slit, then the gap is increased. This increases the amount of glass loaded, thus further increasing the characteristic variations due to the differences in coefficient of thermal expansion. Another problem is that it is difficult to load the glass without creating a gas between the slider 2 and the head core 6 and without producing bubbles.
It is a first object of the present invention to provide a floating magnetic head which is free of the foregoing problems with the prior art techniques, is easy to fabricate, and has excellent High frequency characteristics.
This object is achieved by a first structure which is described later in connection with a first and second examples of the invention.
A second structure of the invention is an improvement over the first structure. In particular, where the head core is exposed, when the winding 9 is mounted or the core is mounted to a suspension in a following step, or when the hard disk drive is mounted or the core is mounted to a suspension in a following step, or when the hard disk drive is mounted or otherwise treated, distortion or impact directly acts on the head core 6. As a result, the core 6 may get damaged or the characteristics may be deteriorated. Furthermore, the winding 9 tends to be disarranged. The disarranged winding 9 may come into contact with the disk, resulting in electrical leakage, breakage, or other trouble. Generally, a bobbin (not shown) is used to prevent the winding from being disarranged or to prevent layer short between the wire of the winding 9 and the head core 6. There arises the possibility that the core 6 is damaged. Accordingly, it is a second object of the invention to provide a floating magnetic head which has a reinforced head core to prevent damage and characteristic deterioration and which suppresses disarrangement of the winding 9, thus preventing electrical leakage and breakage.
Conventionally, in floating magnetic head, a CSS (Contact Start Stop) system is employed, in which the magnetic head is floated by 0.1-0.3 .mu.m from the medium surface while the medium such as a disk rotates at high speed and the sliding surface of the magnetic head 1 is pushed onto the surface of the medium while it stops. During the above operation, since it tends to occur that at the time of CSS operation the surface of the medium is damaged by the edge portion 39 of the slider 2 illustrated in FIG. 1, so that it is desired to avoid such damage i.e. to increase the characteristics of CSS. To this object, there has been carried out on the edge portion 39 of the slider 2 or on the edge of the magnetic head core 6 so as to increase such characteristics of CSS.
Further, to the above floating magnetic head 1, there have been ideas to chamfer the edge portions 39 of the slider 2 or the edge portion of the magnetic head core 6, however, it may chamfer also the edge of the head core 6, which deteriorates the track width t in FIG. 1.
Accordingly, the third object of the present invention is to provide a floating magnetic head which is prevented from being deteriorated in its width so as to increase the CSS characteristics.